/*
 * (c) Copyright 2018 Palantir Technologies Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.palantir.atlasdb.keyvalue.dbkvs.impl.sweep;

import com.google.common.collect.Iterators;
import com.palantir.atlasdb.keyvalue.api.CandidateCellForSweeping;
import com.palantir.atlasdb.keyvalue.api.CandidateCellForSweepingRequest;
import com.palantir.atlasdb.keyvalue.api.TableReference;
import java.util.Iterator;
import java.util.List;

public class DbKvsGetCandidateCellsForSweeping {

    private final CellTsPairLoader cellTsPairLoader;

    public DbKvsGetCandidateCellsForSweeping(CellTsPairLoader cellTsPairLoader) {
        this.cellTsPairLoader = cellTsPairLoader;
    }

    public Iterator<List<CandidateCellForSweeping>> getCandidateCellsForSweeping(
            TableReference tableRef, CandidateCellForSweepingRequest request) {
        Iterator<List<CellTsPairInfo>> cellTsIter = cellTsPairLoader.createPageIterator(tableRef, request);
        Iterator<List<CandidateCellForSweeping>> rawIter = CandidateGroupingIterator.create(cellTsIter);
        return Iterators.filter(rawIter, page -> !page.isEmpty());
    }
}
